Submarine-to-satellite communications antenna

ABSTRACT

A phased-array antenna system for an SHF communications link between submarines and earth-orbiting satellites. The compact antenna system is mounted in the head of a submarine periscope and provides increased data rate, low-sidelobes, variable beam control, multiple-beam capability, and circular polarization. RF energy to be transmitted is conducted from transmitting means in the submarine through a waveguide run the length of the periscope to the antenna system which includes a high-power switch to commute the energy to a four-port hybrid matrix. The matrix feeds selectively predetermined phase progressions of the energy to the radiating array which comprises a plurality of probe-fed, cavity elements.

wir States Patent [191 Boyns Aug. 21, 1973 [75] Inventor:

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Sept. 8, 1972 [21] Appl. No.: 287,309

Jerry E. Boyns, San Diego, Calif.

52 U.S.Cl 343/709, 343/872, 343/854 511 Int.Cl. H01q 1/34 581FieldofSearch 343/709,?10, 872,

[56] References Cited UNITED STATES PATENTS 3,495,261 2/1970 Lastingeret al. 343/709 Primary Examiner-Eli Lieberman Attorney-R. S. Sciascia,George J. Rubens et al.

[5 7 ABSTRACT A phased-array antenna system for an SHF communicationslink between submarines and earth-orbiting satellites. The compactantenna system is mounted in the head of a submarine periscope andprovides increased data rate, low-sidelobes, variable beam control,multiple-beam capability, and circular polarization. RF energy to betransmitted is conducted from transmitting means in the submarinethrough a waveguide run the length of the periscope to the antennasystem which includes a high-power switch to commute the energy to afour-port hybrid matrix. The matrix feeds selectively predeterminedphase progressions of the energy to the radiating array which comprisesa plurality of probefed, cavity elements.

4 Claims, 5 Drawing Figures PATENTED BB2! 8973 SHEET 1 BF 2 FIG.2

FIG.1

PATENTEUAusZI ms 3754.268

SHEEI 2 0f 2 20 RELATIVE POWER ONE WAY (an) 38 o o 0 0 72 36 O 36 72FIG. 4

RELATIVE POWER ONE WAY (db) IO 2O WM WMX SUBMARINE-TO-SATELLITECOMMUNICATIONS ANTENNA BACKGROUND OF THE INVENTION At the present time,an SHF link for providing communication between submarines andearth-orbiting satellites is not availablealthough the need for such alink does currently exist. The inventive concept to be disclosed hereinrelates to a novel phased array antenna which can provide such a linkand which can replace the periscope-mounted radar ranging antennacurrently found in submarines but which cannot provide asubmarine-to-satellite communications link.

SUMMARY OF THE INVENTION A submarine-to-satellite antenna system for anSI-IF communications link between a submarine and an earth-orbitingsatellite is disclosed. The antenna system comprises a compact,relatively small unit which is mounted in an aperture in the head of asubmarine general purpose periscope. RF energy from a transmitter sourcein the submarine is coupled through a waveguide run the length of theperiscope to a high-cover switch in the unit to commute the energy to abeamforming hybrid matrix which provides selectively predetermined phaseprogressions across the radiating aperture of the antenna. The radiatingarray comprises a plurality of probe-fed, cavity elements. A radome ismounted in the aperture to protect the antenna system from theenvironment. In operation the multiple beam capability can be used as abroad beamwidth antenna to acquire the satellite, and after theacquisition, full power can be radiated by a high-gain, narrow beam.

STATEMENT OF THE OBJECTS OF INVENTION The primary object of the presentinvention is to provide a submarine-to-satellite SHF communications linkincluding a phased-array antenna and featuring increased data rate,low-sidelobes, variable beam control, multiple-beam capability, andcircular polarization.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF TI-IE DRAWINGS FIG. 1 is a partial cut-away, sideview of a generalpurpose, submarine periscope having mounted in the headthereof a novel antenna system to be described herein;

FIG. 2 is a front view of the apparatus of FIG. '1;

FIG. 3 is an isometric view of one of the cavity elements of theradiating array 18; and,

FIGS. 4 and 5 are exemplary radiation patterns obtained with the uniqueantenna system to be described hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present inventive conceptcomprises novel phased-array antenna apparatus intended to be usedprimarily in submarine-to-satellite SI-IF communications systems toachieve the following operational characteristics: increased data rate,low-sidelobes, variable beam control, multiple-beam capability andcircular polarization. FIG. 1 represents the preferred embodiment of theconcept wherein a unique, compact, phased-array antenna system ismounted in an aperture in the head of a submarine periscope to providean SH F communications link between the submarine and an earth-orbitingsatellite.

As can be appreciated from FIG. 1, the apparatus comprises a relativelysimple structure incorporating as one of the main features thereof asubmarine, general purpose periscope head 10 as the support structurefor a unique phased-array antenna system which is generally located andmounted in an aperture 12 located below the optical apparatus 14 of theperiscope. The antenna system comprises, in part, an electromagneticwindow or radome 16 which is rigidly supported in the aperture 10 in theperiscope head. The radome is rectangular and is mounted atsubstantially 45 with respect to the vertical axis of the periscope.

One side of the radome is exposed to the atmosphere and is mountedsubstantially flush with the outer portion of the aperture. Since theantenna system will be exposed to adverse ocean and sea environments,the radome 16 must be capable of withstanding diverse elements such ashigh external pressure, high humidity, and high external temperatures.Fused quartz can be used advantageously where high external pressuresand humidity are encountered, and glass-reinforced aluminum phosphatecan be used where high external temperatures are encountered. Fordeep-sea submergence where high humidity is experienced, a thin coatingof teflon or some other moisture resistive material is required.

A radiating array 18 which is also rectangular is positioned in acontiguous manner with the opposite side of the radome and is rigidlysupported in the periscope head. The array comprises a plurality ofprobe-fed, cavity elements which are arrayed in the rectangular area 18in a three-column, four-row manner. The radiating elements of the arrayare described generally in The Bell Systems Technical Journal, Vol.XLII, July 1963, pp. 869-897, and FIG. 3 illustrates in an isometricview one of the elements, 180.

The dimensions of the aperture of the element are selected such that twocross-polarized modes (TE and TE can propagate. The length W, of thecavity is ad justed to produce a phase differential between the twopolarizations to produce circularly polarized fields at the aperture.

The narrow dimension W is adjusted relatively close to cutoff, and thedepth d of the cavity is adjusted to produce the preferred circularpolarization. The lengths L and L, of the probe are adjusted to providethe preferred polarization and the preferred (best) impedance match forthe element from a SO-ohm coaxial input line to free space. The primaryadvantage offered by an array of such elements is that it will providemore than one beam position in the quadrant from horizon to zenith bysimply activating the high-power switch 22 to select one of the fourprobes of the matrix 20.

The four-port hybrid matrix 20 or Butler matrix is electricallyconnected to and rigidly supported behind the array structure 18 in acontiguous manner with one side thereof. The Butler matrix is awell-known device (Electronic Design, April 1961, p. 179) and feedsphase progressions of RF energy to selectively predetermined ones of thecavity elements 180 of the array 18 whereby four separate beams areprovided for sector coverage. The four beams can cover a quadrant ineither the elevation or azimuth planes with a minimum of zero absolutegain and with a fan beam being provided in the plane opposite to thatbeing scanned.

Mounted below the hybrid matrix 24 is a conventional high-power switch22 which has each of its four output ports connected to a different oneof the four input ports of the matrix by means of a correspondingcoaxial cable 22a. The switch can comprise a singlepole, four-throwdevice which commutes RF energy to one of four possible coaxial outputs.

The RF energy is coupled to the switch input from transmitter apparatus(not shown) located within the submarine. A waveguide run 24,approximately the length of the periscope, is connected between theswitch and the transmitter to accomplish the above.

In operation, RF energy from the transmitter apparatus is conductedthrough the waveguide run 24 to the high-power switch 22. The selectedoutput port of the switch couples its output to a corresponding inputport of the matrix 20 wherefore it provides a selectively predeterminedphase progression across the radiating array 18.

One of the four possible main beams is then radiated therefrom dependingupon which of the four input ports of the matrix has been energized. Adetecting device can be connected to any one of the four input ports ofthe matrix to facilitate selection of the radiated beam.

As stated earlier the matrix and array can provide four separate beamsfor sector coverage and the four beams can cover a quadrant in eitherthe elevation or azimuth planes with a minimum of zero absolute gain.

FIGS. 4 and 5 represent typical radiation patterns as measured for thesystem of FIG. I and 2. Specifically, FIG. 4 shows in graphical form thefour beams as measured with the antenna receiving vertically polarizedRF energy, and FIG. 5 shows a measured pattern with the antennareceiving rotating linearly polarized RF energy.

Thus it can be seen that a novel, relatively simple system has beendisclosed for providing SHF communications between a submarine and asatellite by means of a phased-array antenna apparatus mounted andsupported in an all-purpose submarine periscope. The system providesincreased data rate, low-sidelobes, variable beam control, multiple-beamcapability, and circular polarization.

Obviously many modifications and variations of the present invention arepossible in the light of the-above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

For example, variations in the design of the radiating aperture couldallow for mounting of the radome in the periscope head at more nearly aperpendicular angle (less than 45). Also, other types of hybrid matricescould be used advantageously to allow for tilting of the four beams atvarious angles above the horizon, and matrices having more than fourports could be used in conjunction with radiating apertures having thesame number of radiators in the elevation plane to provide sharper beamsfor more precise satellite contact.

Finally, the entire system could be replaced with a non-resonantwaveguide array of cross-slots which would be designed to have a singlemain beam at certain elevation angles. However, this array has a majordisadvantage in that one-half the transmitted power must be dumped intoa load and also each operating area for the submarine between theequator and the Artic would require a new antenna with a given elevationangle for the main beam.

What is claimed is:

l. A periscope mounted phased-array antenna system for use insubmarine-to-satellite communication systems and comprising:

a general-purpose, submarine periscope,

said periscope having a head portion with an aperture on one side andnear the top thereof;

RF energy radiating aperture means mounted and rigidly supported in saidaperture whereby said means can radiate energy into the atmosphere;

energy feed means mounted and rigidly supported inside said periscopehead and being electrically connected to said radiating aperture means;

transmitter means located inside said submarine; and

waveguide means connected between said transmitter means and said energyfeed means to conduct RF energy to said radiating aperture means.

2. The system of claim 1 wherein said radiating aperture means comprisesa rectangular-shaped, electric radome mounted substantially flush withrespect to the exterior of said aperture, and further including arectangular-shaped array of probe-fed, cavity elements mounted behindsaid radome and substantially inside said periscope head.

3. The system of claim 2 wherein said energy feed means comprises afour-port hybrid matrix mounted behind said array of probe-fed cavityelements to energize selectively predetermined ones of said cavityelements.

4. The system of claim 2 wherein said energy feed means comprises aButler matrix.

1. A periscope mounted phased-array antenna system for use insubmarine-to-satellite communication systems and comprising: ageneral-purpose, submarine periscope, said periscope having a headportion with an aperture on one side and near the top thereof; RF energyradiating aperture means mounted and rigidly supported in said aperturewhereby said means can radiate energy into the atmosphere; energy feedmeans mounted and rigidly supported inside said periscope head and beingelectrically connected to said radiating aperture means; transmittermeans located inside said submarine; and waveguide means connectedbetween said transmitter means and said energy feed means to conduct RFenergy to Said radiating aperture means.
 2. The system of claim 1wherein said radiating aperture means comprises a rectangular-shaped,electric radome mounted substantially flush with respect to the exteriorof said aperture, and further including a rectangular-shaped array ofprobe-fed, cavity elements mounted behind said radome and substantiallyinside said periscope head.
 3. The system of claim 2 wherein said energyfeed means comprises a four-port hybrid matrix mounted behind said arrayof probe-fed cavity elements to energize selectively predetermined onesof said cavity elements.
 4. The system of claim 2 wherein said energyfeed means comprises a Butler matrix.